Mounting bracket



April 1949- J. E. MULHEIM I 2,467,770

\ MOUNTING BRACKIET Filed Oct. 8, 1945 WITNESSES: 3 INVENTOR 52.47% JJep/v name/m. 7 fl BY MW ATTO R N E Y Patented Apr. 19, 1949 MOUNTING BRACKET Joseph E. Mulheim, Lima, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 8, 1945, Serial No. 621,082

4 Claims. (01. 171-252) The present invention relates to mounting brackets and, more particularly, to a bracket construction for engine-driven devices, such as aircraft generators, which are mounted on, and driven by, internal combustion engines.

The invention is especially adapted for use with aircraft generators, and similar engine-driven devices, which are mounted directly on an internal combustion engine, but it is to be understood that the invention is not necessarily restricted to this particular application, and the new mounting bracket may be used for mounting a device of any type on a supporting structure. where similar problems are encountered.

Aircraft generators, which supply the electrical loads on aircraft, are usually mounted on a pad on a main engine of the airplane, and driven by a power take-off shaft geared to the engine crankshaft. In the usual arrangement, threaded studs are secured in the mounting pad, and the generator is held in position by nuts threaded on these studs. It is very desirable to make the distance from the mounting pad to the center of gravity of a generator, or other device, mounted in this manner as small as possible, because of the severe vibration to which the generator is sub- Jected. Any reduction in this distance results in a corresponding reduction in the magnitude of the alternating stresses set up in the generator by the vibration. In an aircraft generator, the limit for reducing the distance between the mounting pad and the center of gravity may be taken as the distance from the end of the mounting studs to the ends of the generator field coils plus the necessary electrical and manufacturing clearances, since the other dimensions of the generator are largely fixed by other design considerations. It is desirable, therefore, to make this distance as short as possible, which requires a minimum axial length of the mounting bracket.

The limited space available for aircraft generators, and other accessories, mounted on an airplane engine also makes it desirable to keep the axial length of the mounting bracket as small as possible, since the size and, therefore, the output of the generator is limited by the available space, and a reduction in the length of the mounting bracket permits an increase in the length of the generator itself, with a corresponding increase in output, without exceeding the limits of the available space.

The limited space available for the generator also causes another difficult problem. As indicated above, these generators are usually secured to the engine by means of studs extending from the mounting pad, and nuts threaded on thestuds. It is frequently necessary to remove a generator from its engine and replace it, and in order to do this with reasonable facility, the arrangement of the mounting bracket must be such that the mounting studs and nuts are readily accessible. The limited space available, however, has made it very difilcult to provide reasonable access to the studs and nuts, and this problem has not been satisfactorily overcome in most of the bracket designs which have been used heretofore. Thus, with some brackets which have been used, it has required several hours to remove a generator and replace it, because of the difficulty of reaching the studs and nuts. This is obviously undesirable, especially in the case of generators for use on military aircraft, where speed of maintenance operations is of great importance. Thus, accessibility of the mounting studs and nuts is an important requirement in mounting brackets for aircraft generators, and

similar devices. It is also necessary for the bracket to have sufficient strength and rigidity to withstand the severe vibration resulting from operation of the internal combustion engine on which it is mounted, since the bracket is the most critical part of the generator in this respect.

It will be apparent, therefore, that the provision of a suitable mounting bracket for aircraft generators is a very difficult problem, since the bracket must be kept to a minimum axial length, but must permit ready accessibility to the mounting studs and nuts, and must also provide sufficient strength and rigidity to withstand severe vibration. In addition to these requirements, the bracket, in common with all other types of aircraft equipment, must be of minimum weight. It will be obvious that these requirements are somewhat conflicting, and there has not been available heretofore a bracket design which has satisfactorily met all of these exacting requirements.

The principal object of the present invention is to provide a mounting bracket for a device to be mounted on a supporting structure by means of studs and nuts, which is of minimum axial length, and which permits ready accessibility to the mounting studs and nuts.

A further object of the invention is to provide a mounting bracket for aircraft generators, and similar engine-mounted devices, which is of minimum axial length to permit the center of gravity of the generator to be as close to the sup port as possible, and which provides for maximum accessibility to the mounting studs and nuts erator with a.

l'i ofth e invention. I

.3 I I to permit ease of mounting and dismounting th device, but which is also'very strong and rigid so as to withstand vibration. I

A more specific object of the invention is to provide a mounting'brac'ket for aircraft generators, and-similar devices, which is of minimum faiiial lengthfand of greatrigidity, and which is "desi'gn d fso-ithatthe generator can be'put into breaded-mounting studs with nuts ongmfsmast secured in po- I the-.previously posi- I opermits ready ac-.

s' Itig ht ening operan -easiIy be installed ,oftheinvention e.. c'llowing detailed dection with the accom- I I rtl I in side elevation and partly inlongit dijira euomior an aircraft' gen- I cu ting'bracket embodying the present inventio' "mounted-in position on a mounting pad; 1 F 2 is a 17 1 5 sectional" view of I the bracket, approximatelyon the line IIII of Fig.

1 Fig; 3 is a transversetse'ctional view, similar to Fig. 2, showing a slightly modified embodiment The invention is shown in the drawing as embodied' in a mounting bracket I for an aircraft generator 2,'which isadaptedto be mounted'on a mounting pad3fon an airplane main engine.

The pad 3 is shown as being annular, with a central opening {through which connection may be'made to a power take-off shaft (not shown).

' "The pad 31s provided with threaded studs 5 which are permanently secured in the pad, so'that the generator may be attached by means of nuts 6 threaded. on'thestuds. I The generator-shown in the bet I, which is closed at one end by the mounting bracket I, and at the other end by a bracket I drawing for they purpose of illustration includes a frame mem- 621,083, filed October 8, 1945, and assigned to Westinghouse Electric Corporation.

The mounting bracket I, to which the present invention" is particularly directed, may be made of steel, andv has a generally circular rim portion 23. which is adapted to be secured to the frame I of the generator in any suitable man- .ner, as by welding or brazing, as indicated at 24.- The rim portion 23 is curved inwardly in 1 the axial direction, so that its inner edge 25 extends downover the field windings II to protect ,the'windings whenthe generator is being mounted in position." The bracket I also includes a radia1 flange portion 26 which is adapted to fit on the pad 3, and which may have an annular shoulder 21 to engage the inner periphery of the pad to accurately center the generator on the pad. The flange portion 26 also has a central hub portion 28 in which the bearing I8 is supported. Y

-The rim'portion 23 .and flange portion 26 of the mounting bracket I are joined together by a plurality of integral, longitudinal ribs- 29 which are spaced apart around the circumference of the bracket so as to leave large, unobstructed openings 30 between the ribs. It will be noted that the ribs 29 are relatively thin in the circumferentialdirection, but arequite deep radially, so as to provide great strength and rigidity in the direction of the vibratory stresses to which the bracket is subjected in service, but

"without requiringan excessive amount of material.

I of any suitable construction. An air shield 9 I is preferably attached over the bracket 8 for connection to a blasttube, or other suitable source of cooling air. Pole pieces I0 aresecured in the frame I, and suitable field windings IIare placed "on the pole pieces III. The armature of the generator includes a hollow shaft I2 having a plurality of radial ribs I3. The laminated armature core I4 is supported on the ribs I3 and carries a suitable armature-winding I5,- which is connected to a commutator I6 also supported on the ribs I3. Suitablebrush' rigging I1 is mounted on the. bracket 6 with brushes n aging the commutator I6.

The armature shaft I2 is supported in -ball bearings I8 and. I9, which are :mounted in the brackets I and 8, respectively. The shaft I2 is driven by means of a short drive shaft 20, which is adapted for a splined connection to the power take-off shaft of the engine, and which is co'nnecte'd. to the armature shaft I2 by means of a resilient coupling 2| to absorb the torsional vi-. I {.bration: of the internal 1 combustion engine. I Damping means 22 are preferably also provided to-damp; the torsional vibration. The flexible 'coupling 2| and damping means 22 may be of fany suitable type, andjhave beenshown as being of the type more specifically described and claimed in my copending'application;.Serial No.

portionsj32 of the elongated openings 3|. The.

This construction, therefore, gives the bracket great rigidity butpermits the weight to be. kept low, since the material is used in the most economical manner.

The number of ribs 29 is equal to the number of mounting bolts 5, and the flange 26 has openings. 3| in the-spaces between the ribs for the reception of 'the bolts 5.. As clearly shown in Fig. 2, the openings 3I are elongated, arcuate openings whichare-just wide enough to permit I the bolts 5 to pass through. One end of each of the openings 3| is enlarged, as'indicated at 32, to a size large enough to permit passage of the mounting nuts 6. At the opposite end of each of the openings 3|, a recess 33 is provided, as by ccunterboring, to form a seat for a nut 6.

In mounting the generator in position on the mounting pad 3, the. nuts 6 are first threaded on the studs '5 far enoughto leave Just sufllcient clearance between the nuts. and the pad for the flange portion 26 of the bracket I. The generator is thenplaced in position by placing the flange portion 26 of the bracket I over the studs 5 and nuts 6, the nutspassing thr'oughthe enlarged generator. is then rotated tobring the studs to the other ends of the openings 3!, and the nuts 6 are tightened down into the counterbored recesses 33, which form seats for the nuts; In this way,

the generator is accurately positioned in the-desired angular position, :which is necessary to insure that the terminals of the generator, and the air shield 9,-will be in the proper position to permit connection of the electrical leads and I the blast tube. In placing the generator in position in this mannenfthe inner periphery 26 of the rim portionof the bracket I protects the field coils II from damage, which might be caused by the nuts 6 if they were only partly threaded on, they studs, and if no protection were provided for the field coils, The nuts 6 are readily accessible for ,tightening'by means of anordinary wrench through the large openings :30, and thus the generator can be mounted in position. or dismounted, very easily in spite of the limited space available.

In order to keep the weight to a minimum, it may sometimes be desirable to make the bracket l of a magnesium or aluminum alloy, rather than of steel. When a soft material such as magnesium or aluminum is used, the nuts 6 would tend to dig into the flange portion 26 when tightened down, and, to prevent this, the construction shown in Fig. 3 may be utilized. The construction oi the bracket shown in this figure is identical with that previously described, with the addition of steel plates 35 secured to the inner surface of the flange portion 26 in the spaces 3|! between the ribs 29. The plates 35 may be secured to the flange portion by any suitable means, such as rivets 88, and are provided with elongated openings I1, coinciding with the openings 3! in the bracket itself, and having enlarged portions 38 at one end coinciding with the enlarged portions 32 of the bracket openings. Counterbored recesses 39 are provided in the plates 35 to form seats for the nuts 6 to accurately position the generator, as previously described. Thus, the modification of Fig. 3 differs from the construction previously described only in the use of the steel plates 35 to prevent the nuts 6 from digging into thebracket when a soft material such as magnesium or aluminum is used.

It should now be apparent that a mounting bracket has been provided for aircraft generators, V

or other engine-mounted devices, which meets the exacting requirements for a device of this type in a very satisfactory manner. The axial length of the new bracket is considerably less than has been attainable with any previously used aircraft generator bracket design, thus permitting the center of gravity of the generator to be as close as possible to the mounting pad to reduce the vibratory stresses in the generator. The construction of the bracket is such that the mounting studs and nuts are readily accessible, and the generator is easily put in place on the studs and secured in position merely by tightening the nuts, which have previously been threaded on the studs. and which are readily accessible through the large openings between the ribs of the bracket. so that they can be tightened by means of an ordinary wrench, thus avoiding the necessity for special tools. The bracket has great strength and rigidity so that it can withstand severe vibratory stresses, and its weight can be kept quite low.

The invention has been described with particular references to aircraft generators, but it is to be understood that the new bracket may be used for other engine-mounted devices or, in general, for any device which is to be mounted on a supporting structure by means of a bracket. A specific embodiment of the invention has been shown and described for the purpose of illustration, but it will be apparent that various modifications might be made within the scope of the invention, and it is to be understood, therefore, that the invention is not limited to the specific details of construction shown, but in its broadest aspects it includes all equivalent modifications and embodiments which come within the scope of the appended claims.

I claim as my invention:

1. In a dynamoelectric machine adapted to be mounted on and driven by an internal combustion engine, said machine having a stator member and a rotor member, said stator member having windings thereon, a mounting bracket for said machine, said bracket having a generally circular rim portion secured to said stator member, said rim portion being curved in the axial direction to extend radially inward over said stator windings, a radial flange portion spaced from the rim portion, and a plurality of longitudinal ribs joining the rim portion and the flange portion, said ribs being spaced apart circumferentially of the bracket to leave open spaces therebetween, and said flange portion having elongated, arcuate openings therein in the spaces between the ribs for the reception of mounting studs, each of said arcuate openings having an enlarged portion to permit passage therethrough of a mounting stud with a nut in place thereon.

2. In a dynamoelectrie machine adapted to be mounted on and driven by an internal combustion engine, said machine having a stator member and a rotor member, said stator member having windings thereon, a mounting bracket for said machine, said bracket having a generally circular rim portion secured to said stator member, said rim portion being curved in the axial direction to extend radially inward over said stator windings, a radial flange portion spaced from the rim portion, and a plurality of longitudinal ribs joining the rim portion and the flange portion, said ribs being relatively deep radially and relatively thin circumferentially and being spaced apart circumjerentially of the bracket to leave open spaces therebetween, said flange portion having elongated, arcuate openings therein in the spaces between the ribs for the reception of mounting studs, each of said arcuate openings having an enlarged portion to permit passage of a stud with a nut in place therein, and each of said arcuate openings having a seat for a nut.

3. In a machine adapted to be mounted on and driven by a. prime mover which is subject to vibration, a mounting bracket for said machine, said bracket having a generally circular rim portion secured to the machine, a generally radial flange portion spaced from the rim portion and adapted to engage a mounting surface on the prime mover, a plurality of generally axial ribs joining said rim and flange portions, said ribs being relatively deep radially to have sufllcient strength to withstand vibration and being rela-. tively thin circumferen-tially, the ribs being spaced apart circumferenti-ally of the bracket to provide substantially unobstructed open spaces between the ribs, and said flange portion having elongated, arcuate openings therein for the reception of mounting studs, each of said arcuate openings having an enlarged portion to permit passage of a stud with a nut in place thereon.

4. In a machine adapted to be mounted on and driven by a prime mover which is subject to vibration, a mounting bracket for said machine, said bracket having a generally circular rim portion secured to the machine, a generally radial flange portion spaced from the rim portion and adapted to engage a mounting surface on the prime mover, a bearing for a rotating par-t oi the, machine supported in the flange portion, a. plurality of generally axial ribs joining sai-d rim and flange portions, said ribs being relatively deep radially to have sufficient strength to withstand vibration and being relatively thin circumferentially, the ribs being spaced apart circumferentially of the bracket to provide substantially unobstructed open spaces between the ribs, and said flange portion having elongated, arcuate openings therein for the reception or mounting studs.

I 7 each of said srcuste openinls ham: :1: en- Number larxed portion to permit P ge 0! a stud with 1,435,400 a nut in place thereon. 1.714.484 JOSEPH E. MULHEIM. 1 745547 6 1.766.254 REFERENCES CITED 1 802 9 The following references are of record in the 2139-379 file of this patent: UNITED STATES PATENTS w 230'422 Number' Name Date 801,383 Km: Oct. 10, 1905 Nlmo I M Layne Novfl, 1922 Johnson May 21. 1029 Layne Feb. 4. 1930 Kearney June 24. 1930 Brady Apr. 28, 193i Myers Dec. 6. 1938 lee Apr. 16, 1940 Guignon June 5. 1945 Happe Nov. 4, .1947 

